The impact of accuracy repeat positioning accuracy on the system

For a single-turn encoder, the output code for each revolution of the encoder shaft is repeated. There is no data to determine whether the encoder has rotated 1 revolution  1000 revolutions. For a multi-turn absolute encoder, the output of each axis position is unique during each rotation, without repeating,   exceeding 4096 revolutions.

Resolution refers to the number of measurement segments  units per inch  millimeter per revolution of the encoder shaft  linear scale. The resolution of the shaft encoder can reach 10,000 pulses per revolution (PPR),  it can even reach 40,000 PPR when using the rising  falling edges of the A  B channels for detection, while the resolution of the linear encoder can reach the micron level. In short, the resolution of the selected encoder must be equal to  greater than the application requirements, but the resolution is  the only factor to be considered.

Accuracy  resolution are different, high resolution does  necessarily mean high accuracy,  vice versa. The figure below shows that the distance X is divided into 24 segments  "bits". If X represents an axis that rotates 360°, a circle is divided into 24 parts.

The 24 bits are the resolution, but the 24 bits are  equally divided. In this case, the sensor cannot be used to accurately measure position, velocity,  acceleration.

On the other hand, the distance X is equally divided into 24 parts. Each increment accurately represents 1/24 turn. In this case, the sensor considers both resolution  accuracy during operation. But the accuracy can also be independent of the resolution. A sensor may only have a resolution of 2 parts per revolution, but its accuracy can reach ±6 arc seconds.

The impact of accuracy  repeat positioning accuracy on the system

System accuracy: The performance of an encoder is usually described in terms of resolution rather than measurement accuracy. The encoder can very accurately decompose the motion into precise bits, but the accuracy of each bit is affected by the quality of the motion of the machine under test. For example, if machine parts are deformed under load,  there is a 0.1 inch gap on the drive screw, an encoder with 1000 count points per revolution  an output accuracy of 0.001 inch cannot eliminate the 0.1 inch error. Encoder only

It can reflect the position of the measured axis  cannot improve the basic accuracy of the measured axis movement.

Note: For a specific mechanical design, certain motion measurement errors, such as mechanical clearance  errors in the lead screw  gear system, can be electronically compensated by some more advanced motion controllers.

System repeatability: Repeatability refers to the error of the controlled mechanical parts repeatedly positioned to the same point in the stroke. The repetition accuracy is generally lower than the system resolution, but slightly higher than the system accuracy. A 2500-cycle dual-channel encoder can generate 10,000 pulses per revolution. Usually when using Dynapar encoder, the accuracy of the signal amplified by 4 times is better than ±1 count point.

DEUPREE (Qingdao) Industrial Technology Co., Ltd. is an integrated enterprise focusing on the research  development of automated industrial technology  equipment manufacturing. The company’s products mainly include rotational motion sensors, linear displacement sensors, object recognition sensors, laser rangefinders, process Control  measurement instruments, signal detection systems, signal transmission systems, immature drive systems, UPS safety power supply systems,  automation equipment energy-saving  cleaning auxiliary equipment systems are  limited to this. We can also customize  flexibly customize according to customer needs. Meet the different needs of different customers.